Apparatus and method for fabricating cirucit pattern on conductive surface of circuit board

ABSTRACT

A circuit fabrication device (10) is used to develop production or prototype circuits. A circuit board (16) having a conductive layer (26) provided thereon is placed in a plotter (14). An electrode (20) connected to a power supply (18) &#34;draws&#34; on the circuit board, thereby vaporizing piortions of the conductive layer patterned conductive regions (30) are thus formed on the conductive layer separated by isolation regions (28) where the portions of the conductive layer have been removed by vaporization in defining a circuit pattern on the conductive layer of the circuit board.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to electronic circuits, and moreparticularly to a apparatus and method for producing prototypeelectronic circuits.

BACKGROUND OF THE INVENTION

The development cycle associated with the commercial realization of anelectronic circuit involves several steps. First, the circuit isdesigned schematically, either by hand or using a computer-aided design(CAD) system. The schematic is used to design an initial prototype whichwill be used to test the circuit for operability, and also to developthe mechanical features which will be used in the final product. Severalof the prototypes are then produced for testing. Typically,modifications are made to the prototype leading up to a final workingmodel which will be mass-produced.

In the prior art, A prototype circuit board would need to be producedfor each prototype. This method has several disadvantages. First, thetime and cost of producing multiple prototype circuit boards issignificant. Second, changes to the prototype boards often necessitatesfabrication of new prototype boards, which results in further costs andtime delays.

Therefore, a need has arisen in the industry to provide a apparatus andmethod for producing circuits which is inexpensive and which facilitateschanges to and reproduction of prototype circuits.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method and apparatus forproducing prototypes is provided which substantially eliminates theproblems associated with prior prototype development systems.

In the present invention, an apparatus and method for developing circuitpatterns is provided in which a circuit board having a conductivesurface formed thereon is placed in a plotting device operable toreceive the circuit board. A plotting head is coupled to the plottingdevice for removing portions of the conductive surface from the circuitboard.

In a second embodiment of the present invention, a circuit board havinga conductive surface formed thereon is placed in a plotting deviceoperable to receive the circuit board. An electrode is coupled to theplotting device for removing portions of the conductive surface from thecircuit board by applying a voltage thereto. A computer control plottingdevice moves the plotting head in a predetermined pattern.

This aspect of the present invention provides several technicaladvantages over the prior art. First, the present invention allowscircuits to be created very quickly. .Changes to these circuits can beincorporated as needed with minimum delay. Further, present invention iscost effective for designing prototype circuits.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a perspective view of the present invention;

FIG. 2 illustrates a cross-sectional side view of the circuit boardmaterial; and

FIG. 3 illustrates a top plan view of an exemplary circuit produced bythe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment of the present invention and its advantages arebest understood by referring to FIGS. 1-3 of the drawings, like numeralsbeing used for like and corresponding parts of the various drawings.

FIG. 1 illustrates a perspective view of the circuit fabrication device10 of the present invention In the preferred embodiment, the circuitfabrication device 10 comprises a computer 12 connected to a plotter 14having a circuit board 16 placed therein. A power supply 18 (typicallysupplying about ten volts) is connected between the conductive surfaceof the circuit board 16 (see FIG. 2) and an electrode 20 controlled bythe plotter 14. The electrode should have a sharp pointed tip and can bemade from almost any conductive material. As well as computer control,the plotter 14 includes manual controls 22 for moving the electrode 20under user control.

FIG. 2 illustrates a cross-sectional side view of the circuit board 16.In the preferred embodiment, the circuit board 16 comprises a Mylar filmbase layer 24 having a conductive layer 26 formed thereon. Typically,the conductive layer 26 comprises a copper layer which is sputtered ontothe base layer 24. Gold and platinum conductive layers are alsoavailable from a variety of manufacturers. The electrode 20 is placed inthe plotter 14 where the pin would typically be placed. The electrode 20may be moved vertically such that it is either placed in contact withthe conductive layer 26 or is removed from contact with the conductivelayer 26. The electrode 20 may also be moved in the plane of the circuitboard 16. In the illustrated embodiment of FIG. 1, the electrode 20moves in an X direction and the circuit board 12 moves in a Y direction.However, other plotting devices may receive the circuit board 16 in astationary position and move the electrode 20 in both X and Y directionsto pattern the circuit board.

As illustrated in FIG. 2, when the electrode 20 is placed in contactwith the conductive layer 26 of the circuit board 16, and a voltage isapplied between the electrode 20 and conductive layer 26, the portion ofthe conductive layer 26 proximate the electrode 20 is vaporized. Hence,an isolation region 28 is formed on the circuit board 16. As theelectrode 20 plots, the metal material is vaporized leaving conductiveislands which may be used to connect nodes of the devices used in thecircuit.

FIG. 3 illustrates a exemplary circuit formed using the circuitfabrication device 10. The plotter 14 creates isolation regions 28 by"drawing" on the circuit board 16 with the electrode 20. Conductiveislands 30 are thus formed, separated by isolation regions 28,connecting nodes 32, as desired.

The line widths of the isolation regions 28 may be varied by controllingthe voltage and plotter speed. The resulting conductive regions 30 mayhave a resolution of at least 0.020 inches. The widths of the isolationregions are typically about 0.010 inches, and may be varied somewhat bythe speed of the drawing process; the slower the movement between theelectrode 20 and circuit board 16, the wider the isolation region willbe.

While the plotter may be operated manually using manual controls 22, themost efficient method of drawing circuits is under computer control. Thecircuits can be designed using any CAD program which interfaces to aplotter. Further, it would possible to design a program which wouldautomatically transform an electrical schematic into a circuit diagramto be plotted. Computer control of the plotter allows easy modificationand reproduction of circuits.

The present invention provides significant advantages. The circuitfabrication device 10 may be used to produce both prototype andproduction circuits in the place of ordinary printed circuit boardtechnology. The creation of the circuits may be extremely fast andchanges can be quickly incorporated into the design. The cost of thesystem is low in comparison with other such devices.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. A method for producing an electronic circuitcomprising the steps of:disposing an electrode having an electrode tipin operative relationship with respect to a circuit board having aconductive surface provided thereon; imparting relative movement betweensaid electrode and said circuit board for positioning the electrode tipof said electrode in contact with the conductive surface of said circuitboard; applying voltage between said electrode and the conductivesurface of the circuit board; drawing on the conductive surface of thecircuit board with the electrode tip of said electrode in a plottingpattern while the electrode tip is disposed in contact with theconductive surface and voltage is applied between said electrode and theconductive surface of the circuit board; and removing conductivematerial from the conductive surface of said circuit board to produce acircuit pattern in the conductive surface of said circuit boardcorresponding to the plotting pattern when the electrode tip is incontact with the conductive surface and voltage is being applied betweensaid electrode and the conductive surface of said circuit board.
 2. Amethod as set forth in claim 1, wherein the application of voltagebetween said electrode and the conductive surface of said circuit boardis at a voltage magnitude sufficient to vaporize conductive materialfrom the conductive surface of said circuit board in areas of contactbetween the electrode tip of said electrode and the conductive surfaceof said circuit board.
 3. A method as set forth in claim 1, wherein theelectrode is coupled to a plotting device, and furthercomprising:placing the circuit board having the conductive surfaceprovided thereon in the plotting device; moving the circuit board withthe conductive surface provided thereon via said plotting device in aY-axis direction for disposing the electrode tip of said electrode incontact with the conductive surface of said circuit board; and movingsaid electrode via said plotting device in an X-axis direction withrespect to the conductive surface provided on said circuit board withthe electrode tip of said electrode being movable in the plane of theconductive surface of said circuit board and in contact therewith indefining the plotting pattern under the control of said plotting device.4. A method as set forth in claim 3, further including controlling themovement of said electrode with respect to the conductive surface ofsaid circuit board in tracing out the plotting pattern by a computerinterfaced with said plotting device via execution of a computer programdetermining the plotting pattern.
 5. Apparatus for producing a circuitpattern on a circuit board having a conductive surface provided thereon,said apparatus comprising:a plotting device adapted to receive thecircuit board with the conductive surface thereof exposed forpatterning; an electrode coupled to said plotting device and having anelectrode tip adapted to be disposed in proximity to the conductivesurface on the circuit board; said electrode being relatively movable ina direction substantially normal with respect to the circuit board asreceived by the plotting device for disposing the electrode tip thereofin contact with the conductive surface of the circuit board and forremoving the electrode tip thereof from contact with the conductivesurface of the circuit board; said electrode being further relativelymovable with respect to the circuit board as received by the plottingdevice to enable the electrode tip of said electrode to undergo relativemovement with respect to the circuit board in the plane of theconductive surface thereof; means for applying voltage between saidelectrode and the conductive surface of the circuit board; said plottingdevice drawing on the conductive surface of the circuit board via theelectrode tip of said electrode in a plotting pattern by providingrelative movement of said electrode with respect to the conductivesurface of the circuit board when the electrode tip is disposed incontact with the conductive surface and said voltage-applying means isactuated to apply voltage between said electrode and the conductivesurface of the circuit board; and conductive material from theconductive surface of the circuit board being removed to produce acircuit pattern in the conductive surface of the circuit boardcorresponding to the plotting pattern when the electrode tip is incontact with the conductive surface and said voltage-applying means isactuated.
 6. Apparatus as set forth in claim 5, wherein said electrodeis vertically movable in a direction toward and away from the circuitboard as received by the plotting device for disposing the electrode tipthereof in contact with the conductive surface of the circuit board andfor removing the electrode tip thereof from contact with the conductivesurface of the circuit board.
 7. Apparatus as set forth in claim 5,wherein said electrode and the circuit board are both movable, saidplotting device in which the circuit board is receivable being effectiveto move the circuit board in a Y-axis direction; andsaid electrode beingmovable in a X-axis direction in tracing out the plotting pattern whenthe electrode tip is disposed in contact with the conductive surface andsaid voltage-applying means is actuated to apply voltage between saidelectrode and the conductive surface of the circuit board.
 8. Apparatusas set forth in claim 5, wherein the circuit board comprises a basslayer of Mylar film
 9. Apparatus as set forth in claim 8, wherein theconductive surface on the circuit board is copper.
 10. Apparatus as setforth in claim 5, wherein the voltage applied by said voltage-applyingmeans between said electrode and the conductive surface of the circuitboard is at a sufficient magnitude to vaporize the conductive surface inareas of contact between the electrode tip of said electrode and theconductive surface.
 11. Apparatus as set forth in claim 5, furthercomprising a computer coupled to said plotting device, said computerbeing provided with control means interfacing with said plotting devicefor controlling said plotting device in drawing on the conductivesurface of the circuit board via the electrode tip of said electrode ina plotting pattern as determined by said control means of said computer.